Change default script stop method to co-op instead of abort.

co-op should be more stable as it doesn't abort threads, which can trigger virtual machine instability
This change will be invisible to users as script DLLs are recompiled automatically where necessary, though the change won't take affect until the next simulator restart.
This change has no effect on existing script state.
If you want to continue using abort, set ScriptStopStrategy = abort in the [XEngine] section of OpenSim.ini

OpenSim/Region/ScriptEngine/XEngine/XEngine.cs

@@ -86,6 +86,10 @@ namespace OpenSim.Region.ScriptEngine.XEngine
         /// </summary>
         private int m_StartDelay;
 
+        /// <summary>
+        /// Are we stopping scripts co-operatively by inserting checks in them at C# compile time (true) or aborting
+        /// their threads (false)?
+        /// </summary>
         private bool m_coopTermination;
 
         private int m_IdleTimeout;
@@ -242,7 +246,7 @@ namespace OpenSim.Region.ScriptEngine.XEngine
             m_ScriptConfig = configSource.Configs["XEngine"];
             m_ConfigSource = configSource;
 
-            string rawScriptStopStrategy = m_ScriptConfig.GetString("ScriptStopStrategy", "abort");
+            string rawScriptStopStrategy = m_ScriptConfig.GetString("ScriptStopStrategy", "coop");
 
             m_log.InfoFormat("[XEngine]: Script stop strategy is {0}", rawScriptStopStrategy);